Method and system for improving non-oriented silicon steel plate shape in continuous annealing process

Abstract

The present invention discloses a method and system for improving the plate shape of non-oriented silicon steel in a continuous annealing process, the method comprising the following steps: S1, detecting the temperature distribution of silicon steel along the width direction at the slow cooling outlet; S2, converting the temperature distribution of silicon steel along the width direction into the stress distribution of silicon steel along the width direction; S3, controlling the cooling rate of silicon steel in the width direction based on the stress distribution of silicon steel along the width direction, so that the stress along the width direction of silicon steel is the same. Based on the measured temperature distribution of silicon steel along the width direction, it is converted into stress distribution, and then the opening of each vent of the slow cooling air regulating system is controlled, so that the stress along the width direction of silicon steel is the same, thereby realizing automatic adjustment of the silicon steel plate shape, which greatly improves the plate shape of silicon steel; in addition, because the temperature measuring roller is in contact with the running silicon steel, the temperature measurement error is relatively small, which is conducive to more accurate control of the opening of each vent.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-oriented electrical steel, and more specifically, to a method and system for improving the plate shape of non-oriented silicon steel in a continuous annealing process. Background Art

[0002] Non-oriented silicon steel is mainly used to manufacture the cores of various motors. It is an important soft magnetic material that is indispensable in the power, electronics and military industries, and is also an important metal functional material for energy conservation. With the upgrade of national motor energy efficiency standards, the requirements for non-oriented silicon steel are getting higher and higher. Not only lower iron loss and higher magnetic induction are required to ensure electromagnetic performance, but also a higher stacking coefficient is required to ensure a smaller gap when the core is stacked to reduce the loss caused by leakage flux. Studies have shown that the plate shape of silicon steel products has a direct impact on the stacking coefficient. In order to ensure smooth use by motor manufacturers, silicon steel manufacturers generally screen the plate shape of silicon steel products before leaving the factory and cut off the parts with poor plate shape, but this will also lead to a decrease in the yield rate of silicon steel.

[0003] Predecessors have also done a lot of work on improving the shape of silicon steel. Patent CN103551398B "A method for controlling the shape of hot-rolled coils of non-oriented silicon steel" improves the wedge-shaped qualified rate of hot-rolled silicon steel by setting hot-rolling related rolling and temperature parameters, controlling rolling mills and guide plates, etc.; Patent CN102909223B "A method for controlling edge shape" and patent CN103406365B "A method for intelligent optimization control of cold-rolled strip shape" both control the shape from the aspects of the cold rolling roll system model and rolling model; Patent CN107119180A "Method for improving the shape of non-oriented silicon steel sheets" improves the shape by controlling the heating and cooling aspects of the normalizing process.

[0004] Most of the above methods are aimed at improving the plate shape of silicon steel by controlling the previous process after continuous annealing, but the continuous annealing process is the last process that affects the plate shape in the production process of high-grade silicon steel. It not only has a significant impact on the plate shape of the silicon steel finished product, but if the plate shape of the silicon steel after continuous annealing does not meet the requirements, there will be no other subsequent processes to improve the plate shape. Summary of the invention

[0005] The present invention provides a method for improving the shape of non-oriented silicon steel sheets in a continuous annealing process, aiming to improve the above-mentioned problem.

[0006] The present invention is achieved by a method for improving the shape of non-oriented silicon steel in a continuous annealing process, characterized in that the method comprises the following steps:

[0007] S1. Detect the temperature distribution of silicon steel along the width direction at the slow cooling outlet;

[0008] S2, converting the temperature distribution of the silicon steel along the width direction into the stress distribution of the silicon steel along the width direction;

[0009] S3. Controlling the cooling rate of the silicon steel in the width direction based on the stress distribution of the silicon steel in the width direction, so that the stress along the width direction of the silicon steel is the same.

[0010] Furthermore, the calculation formula for the stress distribution of silicon steel along the width direction is as follows:

[0011]

[0012] Among them, σ x is the stress at position x in the width direction of the steel strip, F T is the continuous annealing tension, A is the cross-sectional area of ​​the steel strip; P is the slow cooling medium pressure in the annealing furnace; ρ is the density of the steel strip; g is the acceleration of gravity; h is the thickness of the steel strip; Δ T x is the temperature difference at position x in the width direction of the steel strip relative to the temperature of the center line of the steel strip; E is the elastic modulus of the steel strip; υ is the Poisson's ratio.

[0013] Furthermore, the cooling speed control method of silicon steel in the width direction is as follows:

[0014] The stress of silicon steel along the width direction is compared with the reference stress;

[0015] If the stress value is greater than the reference stress and its direction is in the same direction as the reference stress, increase the cooling rate of the stress corresponding position during the slow cooling process. If the stress value is less than the reference stress or its direction is opposite to the reference stress, reduce the cooling rate of the stress corresponding position during the slow cooling process.

[0016] Furthermore, the reference stress is the stress corresponding to the centerline temperature of the silicon steel.

[0017] Furthermore, the slow cooling process cools the silicon steel through a slow cooling air regulating system, the vents of the slow cooling air regulating system are evenly distributed along the width direction of the silicon steel, and the opening of each vent is independently controlled;

[0018] Before use, it is necessary to calibrate the cooling area corresponding to the cooling medium of each vent in the width direction of the silicon steel. When the cooling rate needs to be increased in the corresponding area, the opening of the corresponding vent is increased. When the cooling rate needs to be reduced in the corresponding area, the opening of the corresponding vent is reduced.

[0019] Furthermore, the calculation formula for the opening of each vent is as follows:

[0020]

[0021] Among them, γ 基 is the opening of the vent corresponding to the center line of the silicon steel, γx is the vent opening corresponding to position x in the width direction of the steel strip.

[0022] Furthermore, each vent is provided with a solenoid valve with an encoder, and the opening of each vent is controlled based on the solenoid valve.

[0023] Furthermore, the slow cooling medium is nitrogen.

[0024] The present invention is achieved by providing a non-oriented silicon steel plate shape improvement system in a continuous annealing process, the system comprising:

[0025] A temperature measuring roller disposed between the slow cooling outlet and the fast cooling inlet;

[0026] The slow cooling air conditioning system is powered by multiple fans and uses nitrogen as the slow cooling medium. The fan outlet is connected to the air conditioning duct. The vents on the air conditioning duct are evenly distributed along the width of the silicon steel. The opening of each vent is controlled by a solenoid valve with an encoder.

[0027] A controller that is communicatively connected to the measuring roller and the solenoid valve;

[0028] The temperature measuring roller measures the temperature distribution of the silicon steel along the width direction at the slow cooling outlet and sends it to the controller. The controller controls the opening of each vent of the slow cooling air regulating system based on the method for improving the shape of non-oriented silicon steel in the continuous annealing process as described in any one of claims 1 to 8, so as to make the stress along the width direction of the silicon steel the same.

[0029] Based on the measured temperature distribution of silicon steel along the width direction, it is converted into stress distribution, and then the opening of each vent of the slow cooling and air conditioning system is controlled to make the stress along the width direction of the silicon steel the same, thereby realizing automatic adjustment of the silicon steel plate shape, which greatly improves the silicon steel plate shape; in addition, since the temperature measuring roller is in contact with the running silicon steel, the temperature measurement error is relatively small, which is conducive to more accurate control of the opening of each vent. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A flow chart of a method for improving the shape of non-oriented silicon steel in a continuous annealing process provided by an embodiment of the present invention;

[0031] Figure 2 A schematic structural diagram of a system for improving the shape of non-oriented silicon steel in a continuous annealing process provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The specific implementation modes of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0033] The production process of non-oriented silicon steel sheets is as follows: non-oriented silicon steel cold-rolled coil → cleaning before entering the furnace → heating in a continuous annealing furnace → slow cooling → fast cooling → coating → annealing of finished coil. The continuous annealing process includes heating, slow cooling and fast cooling in a continuous annealing furnace.

[0034] Figure 1 A flow chart of a method for improving the shape of non-oriented silicon steel in a continuous annealing process provided by an embodiment of the present invention, the method specifically comprises the following steps:

[0035] S1. Detect the temperature distribution of silicon steel along the width direction at the slow cooling outlet;

[0036] S2, converting the temperature distribution of the silicon steel along the width direction into the stress distribution of the silicon steel along the width direction;

[0037] In the embodiment of the present invention, the temperature distribution of silicon steel along the width direction is converted into stress distribution, and the stress is calculated based on formula (1). Formula (1) is as follows:

[0038]

[0039] Among them, σ x is the stress at position x in the width direction of the steel strip, F T is the continuous withdrawal tension, A is the cross-sectional area of ​​the steel strip, in mm 2 ; P is the pressure of the slow cooling medium in the annealing furnace, the cooling medium is generally nitrogen, unit MPa; ρ is the density of the steel strip, unit g / cm 3 ; g is the acceleration due to gravity, unit is cm / s 2 ; h is the thickness of the steel strip. The thickness of silicon steel does not change during the continuous annealing process. Unit: mm; Δ T x It is the temperature difference between the temperature at position x in the width direction of the steel strip and the temperature of the center line of the steel strip, which can be positive or negative, and the unit is ℃; E is the elastic modulus of the steel strip, the unit is GPa; υ is the Poisson's ratio, the unit is 1.

[0040] Since the centerline temperature of silicon steel is closest to the target temperature in the continuous annealing process, the stress corresponding to the centerline temperature of silicon steel is taken as the reference stress. Δ T = 0, therefore, the expression of the reference stress is as shown in formula (2):

[0041]

[0042] S3. Controlling the cooling rate of the silicon steel in the width direction based on the stress distribution of the silicon steel in the width direction, so that the stress along the width direction of the silicon steel is the same.

[0043] In an embodiment of the present invention, the stress of the silicon steel along the width direction is compared with the reference stress. If the stress value is greater than the reference stress and the direction is in the same direction as the reference stress, it means that the silicon steel is under pressure at this time, and the cooling rate of the stress corresponding position during the slow cooling process is increased. If the stress value is less than the reference stress or the direction is opposite to the reference stress direction, the steel strip is subjected to tensile stress, and the cooling rate of the stress corresponding position during the slow cooling process is reduced.

[0044] In an embodiment of the present invention, the slow cooling process is to cool the silicon steel through a slow cooling air regulating system, which is powered by multiple fans and uses nitrogen as the slow cooling medium. The fan outlets are connected to multiple air regulating ducts, and the vents on the air regulating ducts are evenly distributed along the width direction of the silicon steel. The opening of each vent is controlled by a solenoid valve with an encoder. Before use, it is necessary to calibrate the cooling area corresponding to the cooling medium of each vent in the width direction of the silicon steel. When the cooling rate needs to be increased in the corresponding area, the opening of the vent is increased. When the cooling rate needs to be reduced in the corresponding area, the opening of the vent is reduced.

[0045] In the embodiment of the present invention, the opening of the corresponding vent is controlled based on the ratio of the measured stress value to the reference stress value. Specifically, the opening of each vent is controlled based on formula (3), and formula (3) is as follows:

[0046]

[0047] Among them, γ 基 is the opening of the vent corresponding to the center line of the silicon steel, γ x is the vent opening corresponding to position x in the width direction of the steel strip.

[0048] Figure 2 The structural schematic diagram of the non-oriented silicon steel plate shape improvement system in the continuous annealing process provided by the embodiment of the present invention, for the convenience of explanation, only the part related to the embodiment of the present invention is shown. The system includes:

[0049] A temperature measuring roller disposed between the slow cooling outlet and the fast cooling inlet;

[0050] The slow cooling air conditioning system is powered by multiple fans and uses nitrogen as the slow cooling medium. The fan outlet is connected to the air conditioning duct. The vents on the air conditioning duct are evenly distributed along the width of the silicon steel. The opening of each vent is controlled by a solenoid valve with an encoder.

[0051] A controller that is communicatively connected to the measuring roller and the solenoid valve.

[0052] The temperature measuring roller measures the temperature distribution of the silicon steel along the width direction at the slow cooling outlet and sends it to the controller. The controller controls the opening of each vent of the slow cooling air adjustment system based on the non-oriented silicon steel plate shape improvement method in the above-mentioned continuous annealing process, so as to make the stress along the width direction of the silicon steel the same, thereby realizing automatic adjustment of the silicon steel plate shape, which greatly improves the silicon steel plate shape; in addition, since the temperature measuring roller is in contact with the running silicon steel, the temperature measurement error is relatively small, which is conducive to more accurate control of the opening of each vent.

[0053] The present invention is explained below in conjunction with the following four embodiments. Embodiments 1 to 4 adopt the technical method provided by the present invention, and Comparative Examples 1 to 4 adopt the traditional method, that is, there is no temperature measuring roller between the slow cooling outlet and the fast cooling inlet, and the opening of the vents of the slow cooling air regulating system cannot be automatically adjusted.

[0054] Example 1: High-grade non-oriented silicon steel 50W270 cold-rolled coil is processed by the process of "cleaning before entering the furnace → continuous annealing → slow cooling → fast cooling → coating → annealing finished coil", wherein the slow cooling stage adopts the automatic control model of the vent opening degree described in the present invention, and the finished product has no wave shape defects, the plate shape is good, and the iron loss P 1.5 / 50 =2.501W / kg, magnetic induction B 50 =1.672T, yield rate 96.89%.

[0055] Example 2: High-grade non-oriented silicon steel 35W250 cold-rolled coil is processed by the process of "cleaning before entering the furnace → continuous annealing → slow cooling → fast cooling → coating → annealing finished coil", wherein the slow cooling stage adopts the automatic control model of the vent opening degree described in the present invention, and the finished product has no wave shape defects, the plate shape is good, and the iron loss P 1.5 / 50 =2.305W / kg, magnetic induction B 50 =1.667T, yield rate 96.57%.

[0056] Example 3: The cold-rolled coil of medium-grade non-oriented silicon steel 50W470 is processed by the process of "cleaning before entering the furnace → continuous annealing → slow cooling → fast cooling → coating → annealing finished coil", wherein the slow cooling stage adopts the automatic control model of the vent opening degree described in the present invention, and the finished product has no wave shape defects, the plate shape is good, and the iron loss P is 1.5 / 50 =3.410W / kg, magnetic induction B 50 =1.702T, yield rate 96.96%.

[0057] Example 4: Low-grade non-oriented silicon steel 50W800 cold-rolled coil is processed by the process of "cleaning before entering the furnace → continuous annealing → slow cooling → fast cooling → coating → annealing finished coil", wherein the slow cooling stage adopts the automatic control model of the vent opening degree described in the present invention, and the finished product has no wave shape defects, the plate shape is good, and the iron loss P 1.5 / 50=4.951W / kg, magnetic induction B 50 =1.733T, yield rate 97.13%.

[0058] Comparative Example 1: High-grade non-oriented silicon steel 50W270 cold-rolled coil is processed by the process of "cleaning before entering the furnace → continuous annealing → slow cooling → fast cooling → coating → annealing finished coil", in which the slow cooling section is carried out in a conventional way. The finished product has obvious edge waves, with a wave height of about 5mm. The edge wave area needs to be removed through the finishing process, and the iron loss P 1.5 / 50 =2.499W / kg, magnetic induction B 50 =1.672T, yield rate 94.47%.

[0059] Comparative Example 2: High-grade non-oriented silicon steel 35W250 cold-rolled coil is processed by the process of "cleaning before entering the furnace → continuous annealing → slow cooling → fast cooling → coating → annealing finished coil", in which the slow cooling stage is carried out in a conventional way. The finished product has obvious edge waves, with a wave height of about 3.5mm. The edge wave area needs to be removed through the finishing process, and the iron loss P 1.5 / 50 =2.306W / kg, magnetic induction B 50 =1.666T, yield rate 94.52%.

[0060] Comparative Example 3: The cold-rolled coil of medium-grade non-oriented silicon steel 50W470 is processed by the process of "cleaning before entering the furnace → continuous annealing → slow cooling → fast cooling → coating → annealing finished coil". The slow cooling stage is carried out in a conventional way. The finished product has obvious edge waves, with a wave height of about 4mm. The edge wave area needs to be removed through the finishing process. The iron loss P 1.5 / 50 =3.407W / kg, magnetic induction B 50 =1.702T, yield rate 94.87%.

[0061] Comparative Example 4: Low-grade non-oriented silicon steel 50W800 cold-rolled coil is processed by the process of "cleaning before entering the furnace → continuous annealing → slow cooling → fast cooling → coating → annealing finished coil". The slow cooling stage is carried out in a conventional way. The finished product has obvious edge waves, with a wave height of about 3mm. The edge wave area needs to be removed through a finishing process. The iron loss P 1.5 / 50 =4.947W / kg, magnetic induction B 50 =1.733T, yield rate 95.21%.

[0062] The actual results of the embodiments and comparative examples are shown in Table 1.

[0063] Table 1 Results of Examples and Comparative Examples

[0064]

[0065] The present invention has been described exemplarily. Obviously, the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A method for improving the shape of non-oriented silicon steel in a continuous annealing process, characterized in that: The method comprises the following steps: S1. Detect the temperature distribution of silicon steel along the width direction at the slow cooling outlet; S2, converting the temperature distribution of the silicon steel along the width direction into the stress distribution of the silicon steel along the width direction; S3, controlling the cooling rate of the silicon steel in the width direction based on the stress distribution of the silicon steel in the width direction, so that the stress along the width direction of the silicon steel is the same; The calculation formula for stress distribution of silicon steel along the width direction is as follows: Among them, σ x is the stress at position x in the width direction of the steel strip, F T is the continuous annealing tension, A is the cross-sectional area of ​​the steel strip; P is the slow cooling medium pressure in the annealing furnace; ρ is the density of the steel strip; g is the acceleration of gravity; h is the thickness of the steel strip; Δ T x is the temperature difference between the temperature at position x in the width direction of the steel strip and the temperature at the center line of the steel strip; E is the elastic modulus of the steel strip; υ is the Poisson's ratio; The specific method for controlling the cooling rate of silicon steel in the width direction is as follows: The stress of silicon steel along the width direction is compared with the reference stress; If the stress value is greater than the reference stress and the direction is the same as the reference stress, increase the cooling rate of the position corresponding to the stress during the slow cooling process; if the stress value is less than the reference stress or the direction is opposite to the reference stress, reduce the cooling rate of the position corresponding to the stress during the slow cooling process; The reference stress is the stress corresponding to the centerline temperature of silicon steel.

2. The method for improving the shape of non-oriented silicon steel in a continuous annealing process according to claim 1, characterized in that: The slow cooling process uses a slow cooling air conditioning system to cool the silicon steel. The vents of the slow cooling air conditioning system are evenly distributed along the width of the silicon steel, and the opening of each vent is independently controlled. Before use, it is necessary to calibrate the cooling area corresponding to the cooling medium of each vent in the width direction of the silicon steel. When the cooling rate needs to be increased in the corresponding area, the opening of the corresponding vent is increased. When the cooling rate needs to be reduced in the corresponding area, the opening of the corresponding vent is reduced.

3. The method for improving the shape of non-oriented silicon steel in a continuous annealing process according to claim 2, characterized in that: The calculation formula for the opening of each vent is as follows: Among them, γ 基 is the opening of the vent corresponding to the center line of the silicon steel, γ x is the vent opening corresponding to position x in the width direction of the steel strip.

4. The method for improving the shape of non-oriented silicon steel in a continuous annealing process according to claim 1, characterized in that: Each vent is provided with a solenoid valve with an encoder, and the opening of each vent is controlled based on the solenoid valve.

5. The method for improving the shape of non-oriented silicon steel in a continuous annealing process according to claim 1, characterized in that: The slow cooling medium is nitrogen.

6. A non-oriented silicon steel plate shape improvement system in a continuous annealing process, characterized in that: The system comprises: A temperature measuring roller disposed between the slow cooling outlet and the fast cooling inlet; The slow cooling air conditioning system is powered by multiple fans and uses nitrogen as the slow cooling medium. The fan outlet is connected to the air conditioning duct. The vents on the air conditioning duct are evenly distributed along the width of the silicon steel. The opening of each vent is controlled by a solenoid valve with an encoder. A controller communicatively connected with the measuring roller and the solenoid valve; The temperature measuring roller measures the temperature distribution of the silicon steel along the width direction at the slow cooling outlet and sends it to the controller. The controller controls the opening of each vent of the slow cooling air regulating system based on the method for improving the shape of non-oriented silicon steel in the continuous annealing process as described in any one of claims 1 to 5, so as to make the stress along the width direction of the silicon steel the same.

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